This is a naive but genuine question for non-glider pilots who fly IMC in class G:
Can you be sure that you are aware of other pilots doing the same? In other words, if another pilot is also flying IMC but speaking to a different ATC service, would you receive that information?
And as a supplementary, do all non-glider pilots flying IMC in class G inform ATC of their activities, or are there some who merely monitor one or more frequencies without transmitting?